Open AccessCharacterizations of tropospheric turbulence and stability layers from aircraft observations
Author(s) -
Cho John Y. N.,
Newell Reginald E.,
Anderson Bruce E.,
Barrick John D. W.,
Thornhill K. Lee
Publication year - 2003
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2002jd002820
Subject(s) - turbulence , turbulence kinetic energy , troposphere , advection , atmospheric sciences , richardson number , instability , k epsilon turbulence model , mechanics , physics , convection , boundary layer , meteorology , thermodynamics
Velocity, temperature, and specific humidity data collected by aircraft at 20‐Hz resolution are analyzed for stability and turbulence parameters. Over 100 vertical profiles (mostly over the ocean) with a total of over 300 km in vertical airspace sampled are used. The compiled statistics show that anisotropy in the velocity fluctuations prevail down to the smallest spatial separations measured. A partitioning of convective versus dynamical instability indicates that in the free troposphere, the ratio of shear‐produced turbulence to convectively produced turbulence increases from roughly 2:1 for weak turbulence (ϵ < 10 −4 m 2 s −3 ) to perhaps 3:1 for strong turbulence (ϵ > 10 −4 m 2 s −3 ). For the boundary layer, this ratio is close to 1:1 for weak turbulence and roughly 2:1 for strong turbulence. There is also a correlation between the strength of the vertical shear in horizontal winds and the turbulence intensity. In the free troposphere the turbulence intensity is independent of the degree of static stability, whereas in the boundary layer the turbulence intensity increases with a fall in static stability. Vertical humidity gradients correlate with static stability for strong humidity gradients, which supports the basic notion that stable layers impede vertical mixing of trace gases and aerosols. Vertical shear correlates with vertical humidity gradient, so it appears that the effect of differential advection creating tracer gradients dominates the effect of differential advection destroying tracer gradients through shear‐induced turbulence.